Digital still camera

ABSTRACT

Prior to a photographing operation, an image blur quantity indicating the extent to which the image becomes blurred during the photographing operation is calculated based upon an image-capturing sensitivity having been set, and a decision is made as to whether or not the image-capturing sensitivity needs to be adjusted based upon the calculated image blur quantity. If it is decided that the sensitivity level needs to be adjusted, the image-capturing sensitivity is adjusted and the photographing operation is executed at the shutter speed calculated based upon the adjusted image-capturing sensitivity.

[0001] The disclosure of the following priority application is hereinincorporated by reference: Japanese Patent Application No. 2003-156811filed Jun. 2, 2003

BACKGROUND OF INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a digital still camera, and morespecifically, it relates to a technology for reducing the extent towhich an image becomes blurred.

[0004] 2. Description of the Related Art

[0005] An image blur caused by an unsteady hand movement or the likeduring a photographing operation greatly detracts from the appearance ofthe resulting picture and thus greatly lowers the value of thephotograph. The extent of such an image blur increases as the shutterspeed decreases. Generally, a significant extent of image blur is saidto manifest in a photograph taken by holding a 35 mm camera mounted witha photographic lens with a focal length of f [mm], if the shutter speedbecomes lower than 1/f [sec]. Accordingly, various attempts have beenmade in the related art to reduce the extent of image blur.

[0006] Japanese Laid Open Patent Publication No. H 11-215432 discloses adigital still camera designed to reduce the image blur without having todetect any camera vibration. By taking advantage of a digital stillcamera feature which allows the ISO speed to be adjusted for each frame,the ISO speed level is raised if the calculated shutter speed is lowerthan a hand movement limit value so as to sustain a high shutter speedin this digital still camera. While the shutter speed can be sustainedat a high level by raising the ISO speed, this method has a problem inthat the image quality becomes poor due to noise.

SUMMARY OF THE INVENTION

[0007] A digital still camera according to the present inventioncomprises: a sensitivity setting device that sets an image-capturingsensitivity; a photographing device having an image-capturing elementthat receives a light flux transmitted through a photographic lens andexecutes photoelectric conversion on the received light flux; a controldevice that engages the photographing device in operation at a shutterspeed corresponding to the image-capturing sensitivity set by thesensitivity setting device; an image blur calculation device thatcalculates an image blur quantity indicating an extent to which an imagebecomes blurred during a photographing operation based upon theimage-capturing sensitivity having been set prior to the photographingoperation; and a determination device that makes a decision as towhether the image-capturing sensitivity needs to be adjusted based uponthe image blur quantity calculated by the image blur calculation device,wherein: the sensitivity setting device adjusts the image-capturingsensitivity if the determination device determines that theimage-capturing sensitivity needs to be adjusted; and if theimage-capturing sensitivity is adjusted, the control device engages thephotographing device in operation at a shutter speed corresponding tothe adjusted image-capturing sensitivity.

[0008] It is preferable if the calculated image blur quantity exceeds apredetermined limit value, the sensitivity setting device shifts theimage-capturing sensitivity to a higher level so as to lower the imageblur quantity to a value equal to or less than the limit value.

[0009] It is preferable that the image blur calculation device includesa vibration detection sensor that detects an extent of vibration towhich the digital camera is subjected, and calculates the image blurquantity indicating the extent to which the image becomes blurred duringthe photographing operation based upon detection results provided by thevibration detection sensor and the shutter speed determined inconformance to photometering results obtained by photometering aphotographic field and the image-capturing sensitivity having been set.An optical image blur correction mechanism that reduces the extent ofimage blur based upon an output from the vibration detection sensor maybe further comprised and it is preferable that the determination devicedetermines that the image-capturing sensitivity needs to be adjusted ifthe image blur quantity cannot be lowered to a value equal to or lessthan a predetermined limit value through an image blur correction aloneexecuted by the optical image blur correction mechanism.

[0010] The sensitivity setting device may set the image-capturingsensitivity to a lowest possible sensitivity level within a range overwhich the calculated image blur quantity does not exceed a predeterminedlimit value.

[0011] An image blur correction apparatus according to the presentinvention comprises: a sensitivity setting device that sets animage-capturing sensitivity; an image capturing command output devicethat outputs a signal for engaging an image-capturing element inphotoelectric conversion at a shutter speed corresponding to theimage-capturing sensitivity set by the sensitivity setting device; animage blur calculation device that calculates an image blur quantityindicating an extent to which an image becomes blurred during aphotographing operation based upon the image-capturing sensitivityhaving been set, prior to the photographing operation; and adetermination device that makes a decision as to whether theimage-capturing sensitivity needs to be adjusted based upon the imageblur quantity calculated by the image blur calculation device, wherein:the sensitivity setting device adjusts the image-capturing sensitivityif the determination device determines that the image-capturingsensitivity needs to be adjusted; and when the image-capturingsensitivity is adjusted, the image capturing command output deviceoutputs the signal to the image-capturing element to engage theimage-capturing element in photoelectric conversion at the shutter speedcorresponding to the adjusted image-capturing sensitivity. It ispreferable to further comprise a blur preventing mode switch operated toset/clear a blur preventing mode in which control is implemented toreduce the extent of image blur by adjusting the image-capturingsensitivity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a block diagram of a control system of a digital stillcamera achieved in an embodiment of the present invention;

[0013]FIG. 2 presents a flowchart of control implemented during imageblur correction processing in the camera achieved in the embodiment;

[0014]FIG. 3 presents an external view of the digital still cameraachieved in the embodiment; and

[0015]FIG. 4 is a block diagram of a control system of a digital stillcamera achieved as a variation of the embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] The following is an explanation of an embodiment of the presentinvention, given in reference to drawings.

[0017]FIG. 1 is a block diagram of a control system of a digital stillcamera 10 achieved in the embodiment. FIG. 3 is a schematic externalview of the digital still camera 10 having the control system shown inFIG. 1.

[0018] A photometering circuit 2, a vibration detection circuit 3, afocal length detection circuit 4, an exposure control circuit 5, animage-capturing element 6 and a signal processing circuit 7 areconnected to a CPU 1. The photometering circuit 2 detects the brightnesslevel of a subject by using a photometering sensor 2A and inputs thedetected brightness level to the CPU 1. The vibration detection circuit3 detects the extent of vibration to which the camera is subjected byusing a vibration sensor 3A constituted of an angular speed sensor orthe like and inputs the detected vibration quantity to the CPU 1. Thefocal length detection circuit 4 detects the focal length of aphotographic lens 20 and inputs the detected focal length to the CPU 1.

[0019] The exposure control circuit 5 executes a photographing operation(exposure) by driving a shutter and an aperture (not shown). Theimage-capturing element 6 receives a light flux transmitted through thephotographic lens 20, generates image capturing signals from the lightflux thus received and provides the image capturing signals to thesignal processing circuit 7. The signal processing circuit 7 generatesimage data by executing various types of processing on the imagecapturing signals and provides the image data to a recording circuit 8.The recording circuit 8 records the image data into a recording mediumsuch as a memory card. The exposure control circuit 5, theimage-capturing element 6, the signal processing circuit 7 and the likeconstitute a photographing device.

[0020] In addition, a shutter release switch SW1, which is turned on inresponse to an operation of a shutter release button 30, and a blurpreventing mode switch SW2 operated to set/clear a blur preventing modeare connected to the CPU 1.

[0021] Under normal circumstances, the CPU 1 sets the ISO speed inconformance to a photographer operation and calculates an exposure value(an aperture value and a shutter speed) based upon the ISO speed thathas been set and the photometering output from the photometering circuit2. However, if the blur preventing mode has been set, it calculates theexposure value by automatically adjusting the ISO speed setting asappropriate for the circumstances as detailed later.

[0022] The “ISO speed” was originally a term used in internationalstandards to refer to the sensitivity of silver halide film to light.The term “ISO speed” used in reference to digital still cameras isactually the sensitivity (image-capturing sensitivity) of theimage-capturing element 6 converted to an ISO speed. However, the term“ISO speed” is often used in a general way to refer to theimage-capturing sensitivity of a digital camera and the term is alsoused in this general sense in this specification. It is to be noted thatthe term “image-capturing sensitivity” refers to a control targetquantity to be achieved by adjusting one of; the sensitivity level withwhich the signal charges at the output unit of the image-capturingelement 6 are detected, the amplification gain of a variable gainamplifying circuit (not shown) that amplifies the output from theimage-capturing element 6 and the exposure quantity which is varied byaltering the duty of the operational timing of the image-capturingelement 6.

[0023] In the camera 10 adopting the structure described above, the CPU1 sets the blur preventing mode as the blur preventing mode switch SW2is turned on. In the blur preventing mode, the vibration detectioncircuit 3 is engaged prior to a photographing operation so as to detecta camera vibration quantity indicating the extent of vibration to whichthe camera is subjected due to an unsteady hand movement or the like andto calculate an image blur quantity based upon the vibration quantity.The image blur quantity represents the extent to which the subject imagevibrates and becomes blurred at an image forming plane, i.e., at a lightreceiving surface of the image-capturing element 6, during the exposure.Other parameters such as the shutter speed and the focal length of thephotographic lens 20 are needed in addition to the camera vibrationquantity to calculate the image blur quantity. The shutter speed to beused as a parameter can be calculated based upon the photometeringresults and the ISO speed setting.

[0024] It is to be noted that in a camera having a mechanical shutterused to control the length of time over which the light flux enters theimage-capturing element 6, the length of time over which the shutterremains open is equivalent to the shutter speed. In a camera having anelectronic shutter used to control the length of time over which chargesare stored at the image-capturing element 6, the length of time overwhich the electrical charges are stored at the image-capturing element 6is equivalent to the shutter speed.

[0025] If the image blur quantity having been calculated exceeds apredetermined blur limit value, the extent of the image blur is judgedto be significant and accordingly, the ISO speed is automaticallyshifted toward the higher sensitivity side. The extent to which the ISOspeed is shifted (the number of stages over which the ISO speed isshifted) can be calculated as;

n=log₂ (image blur quantity/blur limit value)  (1)

[0026] By raising the sensitivity by n stages, the shutter speed can beshifted toward the higher side by n stages without further opening theaperture, i.e., without affecting the field depth. It is to be notedthat if n is calculated to be a decimal value, n should be rounded up tothe higher integer to be on the safe side. For instance, if thecalculated value of n is a numerical value between 1 and 2, it should berounded up to 2. By adopting this method, it becomes possible to ensurethat the image blur quantity never exceeds the limit value and thus toensure that the image blur does not become conspicuous in the image.

[0027] It is to be noted that the blur limit value set with regard tothe image blur quantity is a threshold value used to judge as to whetheror not the extent of an image blur occurring in an image is within anallowable range.

[0028] In more specific terms, let us consider a situation in which theISO speed setting is ISO 100 in a camera that allows the ISO speed to beset to ISO 100, ISO 200, ISO 400, ISO 800 or ISO 1600 and the image blurquantity having been calculated is 60 μm. It is generally accepted thatas long as the image blur quantity of a given image blur at the imageforming plane does not exceed 30 μm, the blur does not manifest adiscernible image blur in a regular photographic image. Since thecalculated image blur quantity is 60 μm, a rather conspicuous image blurwill manifest in the photographic image. Accordingly, the shift quantityn is calculated by substituting 30 μm for the blur limit value inexpression (1);

n=log₂ (60/30)=1

[0029] Namely, by raising the ISO speed by one stage, i.e., from ISO 100to ISO 200, the shutter speed can be shifted to the higher sidebyonestate (e.g., 1/60 sec->1/125 sec). Asa result, the image blur quantitycan be reduced from 60 μm to 30 μm. Likewise, if n=2, the image blurquantity can be reduced to 30 μm by shifting the ISO speed by two stagesfrom ISO 100 to ISO 400, and if n=5, the image blur quantity can bereduced to 30 μm by shifting the ISO speed by five stages from ISO 100to ISO 1600.

[0030] When the calculated shutter speed is low, the shutter speed canbe raised by increasing the ISO speed, but, at the same time, the imagequantity is bound to become poorer due to noise. Most experiencedphotographers are likely to know how to hold and operate cameras byminimizing an unsteady hand movement which results in an image blur andare thus likely to be capable of photographing pictures without blurringthe images even when the shutter speed is fairly low. For this reason,experienced photographers will not often want the sensitivity to beraised simply because the shutter speed is low, since it will only lowerthe image quality unnecessarily. However, if the shutter speed thresholdvalue at which the sensitivity is raised is set to a lower value,inexperienced photographers will end up with blurred images.

[0031] In the embodiment, instead of raising the ISO speed based uponthe shutter speed, the image blur quantity representing the extent towhich the image becomes blurred during the exposure is estimated throughan arithmetic operation and the ISO speed is raised based upon thisimage blur quantity. As a result, the extent of image blur can beeffectively reduced by increasing the sensitivity for an inexperiencedphotographer who is not likely to be able to handle his camera with asteady hand. At the same time, if an experienced photographer ishandling the camera with a steady hand, the sensitivity is not raisedunnecessarily and thus, the image quality is sustained at a desiredlevel. In addition, the extent of image blur can be effectively reducedby increasing the sensitivity even for an experienced photographer when,for instance, he is forced to photograph pictures in a situation inwhich some unsteady movement is unavoidable.

[0032] The extent of image blur may be reduced by detecting vibration ofthe camera caused by a hand movement and photographing a picture withthe timing with which the image blur is minimized, or by emitting lightwith a flash unit to reduce the extent of the image blur if thephotographer is forced to take a picture in a fairly shaky state. Whenphotographing a picture with the timing that will minimize image blur,the shutter release timing is not constant, and thus, the photographermay miss a good photo opportunity. When the extent of the image blur isreduced by using a flash unit, the image blur in an image which thephotographer wishes to photograph without using the flash unit cannot bereduced.

[0033] By adopting the embodiment, it is ensured that the photographerdoes not miss a good photo opportunity since the shutter release timingdoes not change in correspondence to the degree of vibration and also,the photographer is allowed to take blur-free pictures without having toemit light with the flash unit. Furthermore, as the camera does not needto be equipped with any expensive device such as an optical image blurcorrection mechanism, the increase in the production cost can beminimized.

[0034]FIG. 2 presents a flowchart of the processing executed by the CPU1 in conformance with the blur preventing control program describedabove.

[0035] The CPU 1 starts up this program as the shutter release switchSW1 is turned on, and it engages the photometering circuit 2 in aphotometering operation in step S1. In step S2, the CPU 1 calculates theaperture value and the shutter speed based upon the photometeringresults and the ISO speed setting.

[0036] In step S3, a decision is made as to whether or not the blurpreventing mode is currently set based upon a signal provided by theblur preventing mode switch SW2. If it is determined that the blurpreventing mode is currently set, the operation proceeds to step S4 toengage the vibration detection circuit 3 in operation and to read thedetection output indicating the camera vibration quantity from thevibration detection circuit 3. In addition, the focal length of thephotographic lens 20 detected and output by the focal length detectioncircuit 4 is read in step S5. In step S6, the image blur quantityindicating the extent of image blur that occurs during the exposure iscalculated based upon the camera vibration quantity and the focal lengthrespectively detected in steps S4 and S5.

[0037] The operation then proceeds to step S7 to compare the image blurquantity calculated in step S6 with the blur limit value (e.g., 30 μm).If the image blur quantity exceeds the blur limit value, the operationproceeds to step S8 to calculate the number of stages n over which theISO speed is to be shifted by using expression (1) presented earlier. Inthe following step S9, the ISO speed is shifted toward the higher sideby n stages calculated in step S8. In step S10, a new shutter speed iscalculated based upon the photometering results obtained in step S1 andthe ISO speed adjusted in step S9. By shifting the ISO speed, theshutter speed can be shifted toward the higher side by n stages.

[0038] It is to be noted that if the ISO speed is already set at thehighest limit, the sensitivity cannot be increased any further andaccordingly, an image blur warning should be issued.

[0039] In step S11, the exposure control circuit 5 is engaged to executeexposure by driving the aperture and the shutter based upon the aperturevalue calculated in step S2 and the most recently calculated shutterspeed. It is to be noted that image signals obtained through theexposure are processed and the like through another routine.

[0040] If, on the other hand, it is determined in step S7 that the imageblur quantity is equal to or lower than the blur limit value, theshutter speed does not need to be raised, i.e., it is not necessary toincrease the ISO speed. Accordingly, the operation simply proceeds tostep S11. In addition, if the blur preventing mode is not set currently,the operation proceeds directly to step S11 from step S3. In thesesituations, the photographing operation is executed at the initial ISOspeed setting and the aperture value and the shutter speed calculated instep S2.

[0041] It is to be noted that certain restrictions may be imposed withregard to the adjustment of the ISO speed setting. For instance, evenwhen the highest ISO speed level in the camera is ISO 3200, ISO 800 maybe set as the upper limit to which the sensitivity can be shifted upwardin correspondence to the image blur quantity so as to prevent the imagequality from becoming markedly poorer. In addition in a mode in whichthe shutter speed is set by the photographer, e.g., a shutter speedpriority mode or a manual mode, any increase in the sensitivity thatwill result in a change in the shutter speed may be disallowed to giveprecedence to the photographer's intent.

[0042] While the sensitivity is raised when the calculated image blurquantity exceeds the blur limit value in the explanation given above,the ISO speed may instead be shifted toward the lower side to improvethe image quality when the calculated image blur quantity is small. Forinstance, if the current initial ISO speed setting is ISO 400 and thecalculated image blur quantity is 10 μm, the ISO speed setting may beadjusted to ISO 200. By lowering the ISO speed by one stage in thismanner, the shutter speed is also lowered by one stage to result in anincrease in the image blur quantity to 20 μm. However, since 20 μm isstill less than the blur limit value 30 μm explained earlier, it is notlikely to manifest as a discernible image blur. If, on the hand, the ISOspeed is lowered to ISO 100, the image blur quantity will increase to 40μm, well over the blur limit value. Accordingly, the ISO speed is notlowered any further than ISO 200 in such a situation. By adjusting theISO speed to the lowest level at which the calculated image blurquantity does not exceed the blur limit value, the image quality can beimproved while, at the same time, preventing a discernible image blur.

[0043] The image blur limit value does not need to be set to 30 μm. Inaddition, while an explanation is given above on an example in which theISO speed is adjusted in an increment of a single stage, it may insteadbe adjusted in units of 1/2 stages, 1/3 stages or even finer increments.Furthermore, while the camera vibration is detected with the vibrationsensor 3A such as an angular speed sensor, the vibration may be detectedwith another type of sensor. Alternatively, instead of utilizing thevibration sensor 3A, the extent of image blur may be detected based uponthe detection results (a so-called through image that is displayed on amonitor of the digital still camera 10 in real time before or after theshutter release button 30 is pressed) output from the image-capturingelement 6 in real time.

[0044] As shown in FIG. 4, an optical image blur correction mechanism 40may be employed in conjunction with the ISO speed adjustment executedbased upon the image blur quantity as explained above. The optical imageblur correction mechanism 40 includes a blur correction lens (not shown)disposed within a photographing optical system, which is allowed to movealong a direction perpendicular to the optical axis. The extent of imageblur is reduced by driving a blur correction optical system thatincludes the blur correction lens based upon the extent of vibration towhich the camera (lens) is subjected detected by the vibration sensor3A. It is to be noted that the optical image blur correction mechanism40 is controlled by a CPU 1A.

[0045] By employing such an optical image blur correction mechanism 40to optically correct the image blur, it becomes possible to reduce theextent of image blur even when the focal length of the photographic lens20 is f [mm] and the shutter speed is lower than 1/f [sec] by two tothree stages. Accordingly, the image blur correction is executed byutilizing the optical image blur correction mechanism 40 alone undernormal circumstances, but if the shutter speed is lower than 1/f [sec]by more than two or three stages, the sensitivity is raised incorrespondence to the image blur quantity as well. Consequently, theimage blur quantity can be kept under the limit value by preventing theshutter speed from becoming low, the effect of which can be furtherenhanced with the optical image blur correction. Namely, the ISO speedis adjusted in correspondence to the image blur quantity if the imageblur quantity cannot be reduced to a value under the limit value simplyby executing the optical image blur correction. Through this method, theimage blur can be corrected even more effectively.

[0046] As explained above, prior to the photographing operation, theimage blur quantity representing the extent of image blur to manifest inthe photograph is calculated based upon the image-capturing sensitivitysetting, and a decision is made as to whether or not the image-capturingsensitivity needs to be adjusted based upon the calculated image blurquantity in the embodiment of the present invention. Since theimage-capturing sensitivity is adjusted only if necessary, thephotographing operation can always be executed at the optimalsensitivity level in correspondence to the skill level of thephotographer or the photographing conditions and, as a result, theextent of image blur can be highly effectively reduced without raisingthe sensitivity unnecessarily.

[0047] It is to be noted that the present invention may be adopted in asingle lens reflex digital still camera instead of the digital stillcamera 10 achieved as a compact camera shown in FIG. 3 as in theembodiment.

[0048] The above described embodiment is an example, and variousmodifications can be made without departing from the spirit and scope ofthe invention.

What is claimed is:
 1. A digital still camera comprising: a sensitivitysetting device that sets an image-capturing sensitivity; a photographingdevice having an image-capturing element that receives a light fluxtransmitted through a photographic lens and executes photoelectricconversion on the received light flux; a control device that engages thephotographing device in operation at a shutter speed corresponding tothe image-capturing sensitivity set by the sensitivity setting device;an image blur calculation device that calculates an image blur quantityindicating an extent to which an image becomes blurred during aphotographing operation based upon the image-capturing sensitivityhaving been set prior to the photographing operation; and adetermination device that makes a decision as to whether theimage-capturing sensitivity needs to be adjusted based upon the imageblur quantity calculated by the image blur calculation device, wherein:the sensitivity setting device adjusts the image-capturing sensitivityif the determination device determines that the image-capturingsensitivity needs to be adjusted; and if the image-capturing sensitivityis adjusted, the control device engages the photographing device inoperation at a shutter speed corresponding to the adjustedimage-capturing sensitivity.
 2. A digital still camera according toclaim 1, wherein: if the calculated image blur quantity exceeds apredetermined limit value, the sensitivity setting device shifts theimage-capturing sensitivity to a higher level so as to lower the imageblur quantity to a value equal to or less than the limit value.
 3. Adigital still camera according to claim 1, wherein: the image blurcalculation device includes a vibration detection sensor that detects anextent of vibration to which the digital camera is subjected, andcalculates the image blur quantity indicating the extent to which theimage becomes blurred during the photographing operation based upondetection results provided by the vibration detection sensor and theshutter speed determined in conformance to photometering resultsobtained by photometering a photographic field and the image-capturingsensitivity having been set.
 4. A digital still camera according toclaim 3, further comprising: an optical image blur correction mechanismthat reduces the extent of image blur based upon an output from thevibration detection sensor, wherein; the determination device determinesthat the image-capturing sensitivity needs to be adjusted if the imageblur quantity cannot be lowered to a value equal to or less than apredetermined limit value through an image blur correction aloneexecuted by the optical image blur correction mechanism.
 5. A digitalstill camera according to claim 1, wherein: the sensitivity settingdevice sets the image-capturing sensitivity to a lowest possiblesensitivity level within a range over which the calculated image blurquantity does not exceed a predetermined limit value.
 6. A digital stillcamera according to claim 2, wherein: the image blur calculation deviceincludes a vibration detection sensor that detects an extent ofvibration to which the digital camera is subjected, and calculates theimage blur quantity indicating the extent to which the image becomesblurred during the photographing operation based upon detection resultsprovided by the vibration detection sensor and the shutter speeddetermined in conformance to photometering results obtained byphotometering a photographic field and the image-capturing sensitivityhaving been set.
 7. A digital still camera according to claim 6, furthercomprising: an optical image blur correction mechanism that reduces theextent of image blur based upon an output from the vibration detectionsensor, wherein: the determination device determines that theimage-capturing sensitivity level needs to be adjusted if the image blurquantity cannot be lowered to a value equal to or less than the limitvalue through an image blur correction alone executed by the opticalimage blur correction mechanism.
 8. An image blur correction apparatuscomprising: a sensitivity setting device that sets an image-capturingsensitivity; an image capturing command output device that outputs asignal for engaging an image-capturing element in photoelectricconversion at a shutter speed corresponding to the image-capturingsensitivity set by the sensitivity setting device; an image blurcalculation device that calculates an image blur quantity indicating anextent to which an image becomes blurred during a photographingoperation based upon the image-capturing sensitivity having been set,prior to the photographing operation; and a determination device thatmakes a decision as to whether the image-capturing sensitivity needs tobe adjusted based upon the image blur quantity calculated by the imageblur calculation device, wherein: the sensitivity setting device adjuststhe image-capturing sensitivity if the determination device determinesthat the image-capturing sensitivity needs to be adjusted; and when theimage-capturing sensitivity is adjusted, the image capturing commandoutput device outputs the signal to the image-capturing element toengage the image-capturing element in photoelectric conversion at theshutter speed corresponding to the adjusted image-capturing sensitivity.9. An image blur correction apparatus according to claim 8, furthercomprising: a blur preventing mode switch operated to set/clear a blurpreventing mode in which control is implemented to reduce the extent ofimage blur by adjusting the image-capturing sensitivity.